Ext.form.ComboBox.prototype.filterBy = function(fn, scope) {
	var ds = this.store;
	ds.filterBy(fn, scope);
	ds.realSnapshot = ds.snapshot;
	ds.snapshot = ds.data;
};

Ext.form.ComboBox.prototype.clearFilter = function(suppressEvent) {
	var ds = this.store;
	if (ds.realSnapshot && ds.realSnapshot != ds.snapshot) {
		ds.snapshot = ds.realSnapshot;
		delete ds.realSnapshot;
	}

	ds.clearFilter(suppressEvent);
};